Effects of the production of primary (fatty acids and amino acids) and secondary (isoflavones) metabolites of soybean leaves in a plant factory by LED light intensity and ethylene treatment

This study was conducted to provide fundamental data for the production of isoflavone-enriched soybean leaves by applying a plant factory cultivation system and the plant hormone ethylene (ETL), thereby enhancing the potential utilization value of soybean leaves.Soybeans were cultivated under different photosynthetic photon flux density (PPFD) conditions (Low, 100 mol m -2 s -1 ; High, 190 mol m -2 s -1 ) and subsequently treated with ethylene to analyze changes in nutritional components, bioactive compounds, and metabolites.The cultivation conditions were classified into four groups, Low control (CTL), Low-ETL, High-CTL, and High-ETL, according to differences in PPFD and the presence or absence of ETL treatment.The analysis showed that -aminobutyric acid contents were 177.61, 145.88, 212.83, and 207.92 mg/100 g, while the total isoflavone contents were 2,239.93, 4,745.33,2,279.57,and 7,654.11g/g, respectively.Notably, -aminobutyric acid content was highest under high PPFD conditions, and total isoflavone content showed the greatest increase when ethylene was applied under high PPFD.In addition, antioxidant activities (2,2-diphenyl-1-picrydrazyl 74.95%, 2,2-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) 94.47%) and enzyme inhibitory activities (-glucosidase 30.13%, pancreatic lipase 19.44%) were most pronounced in the High-ETL condition.These results demonstrate that PPFD and ethylene treatment significantly influence the accumulation of functional compounds in soybean leaves, providing a basis for developing optimal strategies for IESL production.